This monument commemorates the Greenwich Tea Burning, which occurred on December 22, 1774. There are 2 plaques at the monument (visible on the left side of the entrance in the above picture) with information about the event, including:
"In the winter of 1774, the American colonies were struggling to define their future relationship with Great Britain. The British tax on tea had sparked the 1773 Boston Tea Party. The harsh response, to close the port of Boston, lead the First Continental Congress meeting in Philadelphia. Congress's non-importation, non-exportation agreement asked colonists not to buy or sell goods from the mother country as a way of putting economic pressure on England. Not far from this spot, on the dark night on December 22, 1774, some residents of Cumberland County demonstrated their agreement with this recommendation by burning a cargo of British tea." [1]

The Monument, which was dedicated September 30, 1908[2], lists the names of the following men
involved with the Greenwich Tea Burning:[3]

Revolutionary War New Jersey
The online field guide to New Jersey's Revolutionary War historic sites!
Greenwich New Jersey Revolutionary War Sites • Greenwich New Jersey Historic Sites
Greenwich Tea Burning Monument • James Ewing House • Old Presbyterian Cemetery